This invention refers to a female electrical connector normally used to connect electrical equipments, for example solenoid valves, to an electrical energy source.
More in particular, the invention relates to a watertight sealed electrical connector of the type in which the electric wires of a cable are connected to respective contact members of the connector, by screw means.
The aim of the invention is to improve the watertight seal of the connector, in particular in correspondence with a contact junction block and the passing through hole for an anchoring screw, in a rear wall of the connector.
As known, in connectors of the aforementioned type it is necessary to provide a suitable watertight seal, both frontally, between the contact support body of the connector and a contact junction block secured to an electrical appliance, in correspondence with a tubular extension for passage of the electric cable, and with a hole for the insertion of an anchoring screw.
In the connectors normally in use, the front seal is obtained by fitting onto the casing, a flat gasket, molded separately and subsequently fitted on manually, by an operator during the assembling of the connector.
As regards the watertight seal, in correspondence with the hole for the passage of the screw through the rear wall of the casing, in general use is made of an annular rib having a triangular cross-sectional shape, against which the head of the anchoring screw is tightly pressed at the fastening of the connector to a junction block, exerting a sufficiently high driving torque to compress and partially deform the apex of the rib in order to achieve the required seal degree.
Conversely, the watertight seal in correspondence with the tubular extension of the casing, for the passage of the electric cable, is obtained by means of an annular gasket appropriately pressed by a ring nut which can be screwed into the same tubular extension of the outer casing of the connector.
The watertight sealing means normally used in the presently known connectors, have several limits and drawbacks, in that they do not afford a sufficiently tight seal, and are made in such a way as to require greater manipulation during the assembling and the connection of an electric cable to the same connector.
In particular, the watertight seal in correspondence with the anchoring screw is obtained by a simple plastic deformation of the rib inside the hole for the passage of the screw in the rear wall of the casing; since such casing is usually made of rigid plastic material, such as nylon with fibreglass filler, to ensure a sufficiently tight seal it is necessary to exert an appropriate driving torque on the screw by the operator, below which the watertight seal of the connector would not be guaranteed.
As the screw is tightened, the head of the latter plastically deforms the apex of the rib inside the hole; consequently, whenever the connector must be removed and/or disassembled, by loosening the screw, and subsequently reassembled, due to the plastic deformation that said rib has been subjected to, it is no longer possible to guarantee the required tightness of the seal.
As regards to the front seal between the connector and a contact junction block, use is conventionally made of a particular gasket molded separately, which must be fitted onto the outer casing by an operator during the assembling of the connector.
Consequently, an incorrect positioning of such gasket may also jeopardize the watertight seal, and in general its assembling involves an additional manipulation and time consuming for the operator.
The general object of this invention is to provide an electrical connector of the aforementioned kind, provided with improved watertight sealing means.
More in particular, one object of this invention is to provide an electrical connector, as defined above, in which the watertight seal in correspondence with the anchoring screw is obtained, at the insertion and tightening of the same anchoring screw, by suitable elastomeric sealing means which not only guarantees a high tightness degree, but also guarantees that the same tightness degree is made possible even after the connector has been removed and/or disassembled one or more times.
A still further object of this invention is to provide a connector as mentioned previously, in which the front seal is achieved by means of a special gasket defining part of the same contact support body inside the connector.
More precisely, according to the invention an electrical connector has been provided of the type comprising:
an outer casing having a rear tubular extension for the passage of an electric cable;
a contact support body inside the casing, connectable to a contact junction block of an electric apparatus;
in which the connector is mechanically anchored to the junction block by screw means which can be screwed into a threaded hole of the aforesaid junction block; and in which
suitable watertight sealing means are provided between opposite front surfaces of the contact support body and the contact junction block, and in correspondence with the anchoring screw, wherein:
said sealing means comprise a flat shaped annular gasket in elastomeric material which extends between the front surface of the contact support body, the front edge of the casing and a peripheral surface of the contact junction block; and
a tubular sealing element for the anchoring screw co-molded with the annular gasket, said tubular sealing element rearwardly extending from the contact support body, into a passing-through hole in the rear wall of the casing to be tightly urged against a shoulder surface of said hole by the insertion and tightening of the anchoring screw to said contact junction block.
In particular, the front sealing gasket is provided, on both sides, with a step-shaped peripheral edge which is disposing flush to the edge of the lateral walls of the casing, and which is suitably pressed against a facing peripheral surface of the contact junction block to provide a tight seal upon completion of the fastening of the connector to the same junction block.
According to a further aspect of this invention, the tubular sealing element is in the form of a guide bush for guiding the anchoring screw, which extends rearwardly from the contact support body, along a rigid support sleeve; the guide bush ends with a conically flaring or suitably shaped head, which is elastically pressed, by said anchoring screw, against an annular sealing shoulder surface in a passing-through hole of the outer casing of the connector, by means of a dual action of radial expansion and axial compression exerted by a neck portion of the screw during the fastening to the contact junction block.